/**
 * Marlin 3D Printer Firmware
 * Copyright (C) 2016 MarlinFirmware [https://github.com/MarlinFirmware/Marlin]
 *
 * Based on Sprinter and grbl.
 * Copyright (C) 2011 Camiel Gubbels / Erik van der Zalm
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#include "Marlin.h"

#if ENABLED(MESH_BED_LEVELING)

  #define MESH_X_DIST ((MESH_MAX_X - (MESH_MIN_X))/(MESH_NUM_X_POINTS - 1))
  #define MESH_Y_DIST ((MESH_MAX_Y - (MESH_MIN_Y))/(MESH_NUM_Y_POINTS - 1))

  class mesh_bed_leveling {
  public:
    bool active;
    float z_offset;
    float z_values[MESH_NUM_Y_POINTS][MESH_NUM_X_POINTS];

    mesh_bed_leveling();

    void reset();

    float get_x(int i) { return MESH_MIN_X + (MESH_X_DIST) * i; }
    float get_y(int i) { return MESH_MIN_Y + (MESH_Y_DIST) * i; }
    void set_z(int ix, int iy, float z) { z_values[iy][ix] = z; }

    inline void zigzag(int index, int &ix, int &iy) {
      ix = index % (MESH_NUM_X_POINTS);
      iy = index / (MESH_NUM_X_POINTS);
      if (iy & 1) ix = (MESH_NUM_X_POINTS - 1) - ix; // Zig zag
    }

    void set_zigzag_z(int index, float z) {
      int ix, iy;
      zigzag(index, ix, iy);
      set_z(ix, iy, z);
    }

    int select_x_index(float x) {
      int i = 1;
      while (x > get_x(i) && i < MESH_NUM_X_POINTS - 1) i++;
      return i - 1;
    }

    int select_y_index(float y) {
      int i = 1;
      while (y > get_y(i) && i < MESH_NUM_Y_POINTS - 1) i++;
      return i - 1;
    }

    float calc_z0(float a0, float a1, float z1, float a2, float z2) {
      float delta_z = (z2 - z1) / (a2 - a1);
      float delta_a = a0 - a1;
      return z1 + delta_a * delta_z;
    }

    float get_z(float x0, float y0) {
      int x_index = select_x_index(x0);
      int y_index = select_y_index(y0);
      float z1 = calc_z0(x0,
                         get_x(x_index), z_values[y_index][x_index],
                         get_x(x_index + 1), z_values[y_index][x_index + 1]);
      float z2 = calc_z0(x0,
                         get_x(x_index), z_values[y_index + 1][x_index],
                         get_x(x_index + 1), z_values[y_index + 1][x_index + 1]);
      float z0 = calc_z0(y0,
                         get_y(y_index), z1,
                         get_y(y_index + 1), z2);
      return z0 + z_offset;
    }
  };

  extern mesh_bed_leveling mbl;

#endif  // MESH_BED_LEVELING
